This invention relates to a new process for preparing a copolyamide comprising polymerizing an alpha, beta-unsaturated nitrile, water and a lactam.
The preparation of a polyamide from acrylonitrile and water is disclosed in U.S. Pat. Nos. 3,629,203 and 3,499,879. The ring opening addition polymerization of caprolactam is also known and is carried out by adding a catalytic amount of water to open the ring and then later removing the water at an elevated temperature. Surprisingly, applicants have discovered that although these polymerizations proceed by different mechanisms the alpha, beta-unsaturated nitrile, water and lactam can be polymerized together to form a copolymer under the appropriate reaction conditions.
The process of this invention results in high yields of a copolyamide which has particularly good physical properties. Moreover, the percent water insolubility and the structure of the resultant copolyamide can be varied by varying the reaction conditions.